The now increasingly ubiquitous air-conditioner (AC) in our houses would easily make it to the list of the top environmental criminals. Why? Just consider these facts. In Delhi, a mere 1°C drop in temperature leads to a 400 MW drop in demand for electricity. This is because ACs account for some 30 per cent of Delhi’s electricity demand and over 60 per cent of its peak demand, according to the data of the Bureau of Energy Efficiency (BEE). In fact, the peak demand hour for electricity is changing. Now instead of evening—traditionally this is when people reach home and switch on lights—it is late afternoon. This is when the household and commercial electricity-usage hour is coinciding. So it is ACs that determine electricity demand and will determine energy efficiency and security.
So how efficient are the ACs sold in India? More importantly, if they are rated to be energy-efficient do they perform as efficiently? Sunita Narain and her colleagues at the Centre for Science and Environment (CSE) decided to find out by getting branded ACs rated five-star by BEE tested for performance. The tests reveal that there was a dip of 2.5 per cent in energy efficiency for every degree rise in temperature. In this way, a five-star AC performed worse than a one-star AC when temperature was 45°C. Why does this happen?